The invention relates to casters in general, and more particularly to improvements in casters of the type wherein the wheel and/or the frame for the wheel can be held against rotation by a blocking device which is movably mounted in the frame.
It is known to provide a caster with a blocking device in the form of a braking lever which is biased to inoperative position but can be pivoted to an operative position in which the lever prevents the wheel from rotating relative to the frame and/or prevents the frame from turning relative to its support, e.g., a support which is attached to a piece of furniture or to any other part which is mounted on one, two or more casters. The means for pivoting the lever to its operative position can include a pedal which is pivotably mounted in the frame and has a projecting arm which can be depressed by a boot or by another article of footwear (or by hand) to pivot the braking lever to the operative position.
German Pat. No. 1,303,706 to Mobus discloses a caster with a wedge-like braking lever which is a leaf spring and whose apex is disposed in the space beneath the web of an inverted U-shaped frame for the wheel of the caster. The braking lever has an upper leg and a lower leg, and these legs can be spread apart by a pedal which is pivotably mounted in the frame and defines with the lower leg of the braking lever a hinge providing a pivot axis for the pedal. The upper leg of the braking lever has a slot for a projection of the pedal so that the pedal is confined to controlled angular movements about the pivot axis. The pedal must be depressed in order to pivot the braking lever to the operative position, and the pedal must be pivoted in the opposite direction in order to enable the braking lever to reassume the inoperative position. As a rule, the pedal is depressed by an article of footwear, and the same article of footwear can be used to pivot the pedal in the opposite direction so as to enable the braking lever to permit angular movements of the frame relative to its support and/or angular movements of the wheel relative to the frame. The just described mode of pivoting the pedal is not entirely satisfactory, especially if the pedal is to be depressed or lifted by a female operator. Moreover, the lifting of the pedal can entail damage to the article of footwear, especially separation of the sole from the upper.
German Pat. No. 2,459,580 to Tente-Rollen (corresponding to U.S. Pat. No. 4,035,864) discloses a modified caster wherein the braking lever can oppose or prevent rotation of the frame relative to the support as well as rotation of the wheel relative to the frame. The braking lever is pivotably mounted in the frame and can be pivoted by a pedal which is also pivotable in and is supported by the frame. A portion of the pedal extends from the rear end of the frame and can be depressed by an article of footwear so as to pivot the braking lever to the operative position. The pedal comprises a depressible resetting member which projects upwardly through and beyond the web of the inverted U-shaped frame and can be depressed by an article of footwear to thereby return the pedal to a position in which the braking lever is free to assume its inoperative position. Depression of the pedal for the purpose of pivoting the braking lever to operative position entails a pivotal movement of the resetting member to a position in which it must be pushed from one side in order to permit return movement of the braking lever to its inoperative position. The web of the frame has a relatively large slot for the resetting member, and a substantial portion of such slot is free for penetration of impurities into the frame of the caster when the braking lever is held in the operative position. This is particularly undesirable if the caster is used on pieces of furniture and/or on other mobile structures in a hospital, in a kitchen or in a like establishment where certain foreign matter which penetrates into the interior of the frame can constitute a breeding ground for bacteria. Moreover, the orientation of the resetting member in the operative position of the braking lever is such that the operator must maintain her or his foot in an awkward position (with the underside of the sole of the article of footwear in a nearly vertical plane) in order to pivot the pedal back to that position in which the braking lever is inoperative. Still, further, it is often difficult or plain impossible to find sufficient room for such orientation of an article of footwear when the caster is located adjacent a wall or another immovable part while the blocking lever is held in the operative position.
Casters with means for blocking rotation of the wheel and/or for preventing the wheel frame from swiveling relative to its support are further disclosed in commonly owned U.S. Pat. Nos. 4,658,466 (granted Apr. 21, 1987 to Vollberg et al.) and 4,720,893 (granted Jan. 26, 1988 to Mellwig et al.).